package leetcode.editor.cn;

//给你一个由 '1'（陆地）和 '0'（水）组成的的二维网格，请你计算网格中岛屿的数量。 
//
// 岛屿总是被水包围，并且每座岛屿只能由水平方向和/或竖直方向上相邻的陆地连接形成。 
//
// 此外，你可以假设该网格的四条边均被水包围。 
//
// 
//
// 示例 1： 
//
// 
//输入：grid = [
//  ["1","1","1","1","0"],
//  ["1","1","0","1","0"],
//  ["1","1","0","0","0"],
//  ["0","0","0","0","0"]
//]
//输出：1
// 
//
// 示例 2： 
//
// 
//输入：grid = [
//  ["1","1","0","0","0"],
//  ["1","1","0","0","0"],
//  ["0","0","1","0","0"],
//  ["0","0","0","1","1"]
//]
//输出：3
// 
//
// 
//
// 提示： 
//
// 
// m == grid.length 
// n == grid[i].length 
// 1 <= m, n <= 300 
// grid[i][j] 的值为 '0' 或 '1' 
// 
// Related Topics 深度优先搜索 广度优先搜索 并查集 数组 矩阵 👍 1831 👎 0

//Java：【200】- 岛屿数量
public class LeetCode_200_NumberOfIslands{
    public static void main(String[] args) {
        Solution solution = new LeetCode_200_NumberOfIslands().new Solution();
        // TO TEST
    }
    
    //leetcode submit region begin(Prohibit modification and deletion)
class Solution {
        private int[] dx = new int[]{1,0,-1,0};
        private int[] dy = new int[]{0,1,0,-1};

    public int numIslands(char[][] grid) {
        int count =0;
        int m = grid.length, n = grid[0].length;
        for (int i = 0; i < m; i++) {
            for (int j = 0; j < n; j++) {
                if(grid[i][j] == '1'){
                    go(grid, i,j);
                    count++;
                }
            }
        }
        return count;
    }

    public void go(char[][] grid, int x,int y){
        if(x<0 || x>= grid.length) return;
        if(y<0 || y>=grid[0].length) return;
        char in = grid[x][y];
        if(in == '1'){
            grid[x][y] = '2';
            for (int k = 0; k < 4; k++) {
                go(grid, x+dx[k], y+dy[k]);
            }
        }
    }
}
//leetcode submit region end(Prohibit modification and deletion)

}